immune response of T cells in cutaneous leishmaniosis

Abstract

The role of TCD4+ cell subsets, Th1 and Th2, has been studied in the infection by Leishmania major in the murine model. The development of the Th1 phenotype in inbred strains of mice (cells that mainly secrete IL.2, IFN.y and TNF.13) are associated with resistance to L. major infection. In contrast, Th2 phenotype (cells that mainly secrete IL.4, IL.5, IL.6, IL.10 and IL.13) are associated with susceptibility to the infection. Recent data suggest than IL.4 appears to be essential for the priming and maturation of Th2 cells while IL.12 enhances the maturation of Th1 cells. In addition, IL.4 and IFN.y exert opposite regulatory effects on Th1 and Th2 cells, respectively. Recent findings have clearly established that the CD8+ T cell subpopulations also contribute to the resolution of the disease and resistance against infection. In humans, although the specific immune response against the parasite is less polarized than in mice, there is a clear tendency to the development of the Th1 phenotype in the mild forms of cutaneous infection. Identification of specific Leishmania.reactive T cell subpopulations in susceptible and resistant individuals should lead to the development of appropriate in vitro assays that could be used for the identification of Leishmania antigens against which a protective immune response is elicited to test as potential vaccine candidates.